Breakup for Western Hudson Bay (WHB) is looking to be later than usual this year, given that the average breakup date since 1991 has been July 1 (using a 30% threshold) – only a few days from now – and the ice in WHB is nowhere near 50% coverage, let alone 30%.
Note that few WHB bears come off the ice around Churchill – most come ashore along the southwest coast of Hudson Bay (almost into SHB) and make their way north over the course of the summer to meet the ice as it reforms in the fall north around Churchill – that’s why it’s called a “migration.”
There’s still a lot of ice left in Hudson Bay, as the Canadian Ice Service map for 29 June 2016 (below) shows:
It seems to me that breakup for WHB this year is looking rather like 2014, which was something like a week later than the average since 1991, but time will tell. See below for comparison to 2009 (a late breakup year), 2015, and 2013 (lots of variability!), as well as a discussion of when bears come ashore in relation to this sea ice breakup benchmark.
Posted in Life History, Sea ice habitat
Tagged 30 percent coverage, breakup, Cherry, Churchill, early breakup, late breakup, onshore, polar bear, sea ice, Southern Hudson Bay, variability, western hudson bay
The region inhabited by the Davis Strait subpopulation of polar bears dips as far south as James Bay and has a history of highly variable sea ice coverage.
For the last two years Davis Strait sea ice in March has been well above average, while other years it been well below. You might be surprised to hear that 1969 had the lowest February/March ice coverage over the entire the 1969-2002 record (Johnston et al. 2005: 211), which ice charts show now extend to 2015 (see below). Reports of sealers working north of Newfoundland and in the Gulf of St. Lawrence in the first few decades of the 20th century show this variability has likely always been a characteristic of the area (Ryan 2014).
Remarkably, this year’s ice coverage for the first week in January is well above what they were in 2014 and 2015 – even though those two years were above average by March. In fact, there hasn’t been this much polar bear habitat in the Southern Labrador Sea in the first week of January since at least 1993.
Posted in Life History, Sea ice habitat
Tagged Atlantic Canada, Canadian Ice Service, Davis Strait, East Coast, facts, James Bay, Labrador Sea, polar bear, sea ice, sealers, variability, winter
I have a new paper out that explains a fundamental problem with polar bear conservation.
I’m convinced that a flawed and out-dated ecological concept — that sea ice, under natural conditions, provides a stable, predictable habitat — is what has allowed the present doom and gloom attitude of most polar bear specialists to develop.
Sea ice changes, of course, from season to season. However, the concept that sea ice is a stable habitat assumes that these seasonal changes are predictable and virtually the same from one year to the next – at least, similar enough that the differences are not responsible for causing marked declines in population size.
The assumption is that under natural, stable conditions populations of Arctic animals will either stay the same over time or increase. Biologists were taught at university that sea ice should be a stable habitat and as a result, they’ve glossed over evidence they collected to the contrary. [see recent posts here and here, for example]
Negative effects on populations of short-term natural variations in spring sea ice or spring snow cover on sea ice have been entirely ignored in modeled predictions of future conditions. The focus has been on summer ice extent.
I have summarized this evidence in a fully referenced, peer-reviewed essay that explores how the acceptance of this fallacy (“sea ice is a stable habitat”) has so skewed the conservation biology of polar bears that to outsiders it may look like a scientific integrity issue.
The summary and the essay are below (with embedded links and references). The Global Warming Policy Foundation (GWPF) has published the essay in their “Briefing Paper” series (#16, The Arctic Fallacy: Sea Ice Stability and the Polar Bear), which includes a must-read foreword by Dr. Matthew Cronin, Professor of Animal Genetics at the University of Alaska Fairbanks. Press release here, pdf here.
I think you’ll find it timely and thought-provoking.
Posted in Conservation Status, Sea ice habitat
Tagged Beaufort Sea, climate change, Cronin, ecology, global warming, GWPF, habitat, Hudson Bay, IUCN Polar Bear Specialist Group, K-selection, model, PBSG, polar bear, Polar Bears International, polarbearscience, population size, predictions, ringed seal, sea ice, snow depth, stable, summer, thick spring ice, variability